Process and apparatus for cross-rolling and expanding tubes.



v R. G. STIEPEL. PROCESS AND APPARATUS FOR GROSS ROLLING AND EXPANDING TUBES.

APYLIOATION FILED JULY 3, 1912.

Patented Oct. 28, 1913.

HTETS-SHEET l.

R. c. sTIBFBL. PROCESS AND APPARATUS FOR GROSS ROLLING AND EXPANDING TUBES.

APPLICATION FILED JULY 3, 1912.

Patented Oct. 28, 1913.

2 SHEETS-SHEBT 2.

Inventor:

M W K fi 'A w,

II: iavl RALPH CHARLES STIEFEL, OF ELLWOOD CITY, PENNSYLVANIA.

PROCESS AND APPARATUS FOR CROSS-ROLLING- AND EXPANDING TUBES.

Specification of Letters Patent.

Patented Oct. 28, 1913.

Application filed July 3, 1912. Serial N 0. 707,501.

To all whom it may concern:

Be it known that I, RALPH' CHARLES STIEFEL, a resident of'Ellwood City, in the State of Pennsylvania, have invented certain new and useful Improvements in Processes and Apparatus for Cross-Rolling and Expanding Tubes, of which the following is a specification, accompanied by drawings.

The invention is particularly designed and intended for expanding and elongating tubes or tubular billets in the heated state in the manufacture of seamless steel and other tubes.-

The principal object of the invention in its most preferred form is to accomplish by a cross rolling of the metal of the tube progressively and simultaneously a rapid and easy expansion 'andelongation and reduction of wall thickness.

In the best form of the process known to me I accomplish the expansion and elongation by forcing the metal to flow longitudinally and transversely under pressureofa convex rolling body against a mandrel which internally supports the tube; and I advance the tube, after leaving one pair of rolls, to a larger diameter of the mandrel bar and roll it thereupon under the succeeding pair of rolls. As the tube advances farther, I subject it to smoothing action be tween rolling faces that are flat in the longitudinal direction of the pass and approximately parallel with the pass, thus giving to the tube a substantially true, smooth and cylindrical surface.

In the drawings: Figure l is a diagram- Inatictop or plan 'view of. onearrangement of apparatus for carrying out the invention; Fig. 2 is a side elevation, partly in longitudinal section, of the same; Fig. 3 is a plan view of another form of the apparatus; Fig. 4 is a partial side elevation of the same,

)artl in section F i 5 shows a different 1 y a a arrangement of the rolling bodies of a pair for use in carrying out the invention; in Figs. 6 and 7 are views of different forms of the rolls of a pair for use in carrying out the invention; and Figs. 8 and 9 are plan and side view partly sectional, showing another variation of the invention.

In the drawings the essentials have been shown and, forthe sake of clearness, the housings, bearings, billet guides and other parts not necessary to the understanding of the invention are omitted.

In the embodiment of apparatus for performing the process illustrated in Figs. 1 and 2, the rolling bodies are three pairs of overlapped disk-shaped rolls, having horizontal axes raised above the plane of the axis of the pass, so as to give a feeding action in addition to the cross rolling action, as well understood. The axes of each roll pair are parallel and the working faces of the rolls are overlapped, as shown. The rolls are slightly but sufliciently inclined in the horizontal plane to the axis of the pass to allow clearance for the billet or tube.

The rear portion of roll A acts on the billet at points opposite the forward portion of roll B. The otherpairs ofrolls C, D and E, F are similarly overlapped.

For convenience in explaining the process, the section of each roll in F ig- 1 is taken as follows: The roll A is sectioned horizontally from its axis toward the lefthand side in the plane of the axis 3%, Fig. 2. On the active side, or righthand side, of the axis the section plane descendsand then corresponds with the axial line of the pass marked j j, as indicated by the section line in Fig. 2. The other rolls are each similarly sectioned, one-half horizontally through the axis, and the other half through bro-ken planes passing down from the axis andthen along the: axial line of the pass. This gives the slightly one-sided appearance to the sections which may be noticed in Fig. 1. I The arrows on the rolls A, B, C, D, E, F in Fig. 2 show the direction of rotation of the rolls. The mandrel bar of progressively increasing diameter, as later explained, is. shown at J and the billet 'or tube at K. The mandrel bar J is provided at its rear end with a screw thread and thereby connected to a spindle G which is mounted .to revolve ma slide head H, but is held firmly against endwise motion in said slide head by the pro ecting thrust collars I. The slide head- H 15 connected to the .piston rod L and piston M. The piston M is movable in cylinder N and may be subjected to a pressure "of fluid on either side, or pressure may be admitted through It, or exhaust against such pressure permitted and controlled by valve S, as later explained. The cylinder N is mounted on the frame 0, which is provided with guideways P which fit and engage flange-like guiding projections Q of the slide head H. The axes of the first pair of rolls A, B are the least raised above the axis of the pass, and the axes of the succeeding pairs of rolls C, D and E, F are raised progressively higher above the axis of the pass to give progressively greater feeding components of rolling motion. It will be understood that the succeeding pairs of rolls C, D and E, F, which act progressively and simultaneously with the rolls A, B upon the billet during the greater portion of its length, may give successively greater feeding effects to the billet, due to two causes:

firstly because their distances above the axis of thepass are successively greater, which gives a greater longitudinal component of their rolling motion, and secondly because they are preferably driven faster in propor tion to the larger diameters of the billet.

To produce an effect of stretching the metal of the billet both longitudinally and transversely to the axis of the billet, i. 6., in order to elongate and expand the billet, the working surfaces of the rolls should be convex and long longitudinally of the pass,

so as to form between them a slowly converging and diverging pass, thus permitting in a restricted measure the spreading and How of the metal longitudinally from beneath the rolling surfaces while at the same time actively cross rolling and expanding it transversely. By convex I mean to include somewhat angular, as well as truly curvilinear convexity, as shown in Fig. 7

, It will be understood that the longer or flatter the contacting working surfaces are longitudinally of the pass, the more difficult it is for the metal to spread or flow longitudinally from beneath them and the greater will be the expanding eflect on the billet relatively to the elongation produced. Thus, if little elongation of the billet and principally expansion is desired, the working faces of the rolling bodies should be more nearly fiat and parallel than where considerable elongation is desired. Flatfaced rolls, like the last pair of rolls E, F in Figs. 1 and 3, produce substantially no elongation of the metal in their action. More power will be required to accomplish the same reduction of wall thickness with flatter than with more convex roll faces, because the metal is not given the same facility to flow in all directions from beneath flat and parallel working surfaces as from beneath longitudinally convex working surfaces.

In order to fully maintain in the billet the expansion produced by any one of the roll pairs, I preferably proportion the feeding action of the succeeding roll pairs so that they do not produce any endwise pull on the metal of the billet; the distances of the axes of the rolls above the axis of the pass should, therefore, be made to successively increase for the successive roll pairs in substantially such amount as, taking into calculation the speed of each roll, gives a feeding effect appropriate to the elongation and reduction of sectional area of the billet by the respective roll pairs. It will, of course, be understood that the longitudinal feed effect of the rolls depends on both the roll speed (linear speed) and the distance the roll axes are raised above the axis of the pass; said distance, for convenience sake, may be called the eccentricity of the rolls. The speed and the eccentricity of each roll pair should preferably bearranged so that substantially no resulting endwise pull on the metal is produced, in order to maintain the expansion of the billet, and so that the rotary speed (angular speed) of the billet, although enlarged successively, be substantially the same between all the coacting roll pairs, in order preferably to prevent twisting the billet. Twist, however, if desired for some uses, may be imparted to the billet or tube by proportioning the roll speeds so that the rotary speed imparted to the billet varies between the different roll pairs. The last pair of rolls E, F have their working faces substantially flat and parallel with the pass for the purpose of smoothing or cross rolling out any spiral grooves or depressions rolled into the outer surface of the billet by the convex working surfaces of the preceding roll pairs. These flat working surfaces forming a substantially parallel pass between them give the metal which is subjected to the cross rolling while on the cylindrical mandrel J little or no opportunity and tendency to. flow longitudinally. Their purpose is not to effect reduction of the wall of the tube, but to produce a smooth, cylindrical surface on the tube.

It will be understood that the wall of the billet or tube, while being first cross rolled and reduced in thickness in the converging portion of the pass between the convex working surfaces of the rolls and the mandrel, assumes an oval section due to the expansion resulting from the cross rolling action, but as the oval billet further progresses spirally through and out from the diverging portion of the pass, its shape is gradually changed from oval to round, the consequence being that the diameter of the billet or tube as it leaves the working faces of the rolls is larger than the diameter of same as enters between said working faces. The opening between the rolls of the next succeeding pair, in order to accommodate the 'tube as expanded by the preceding pair and further act upon it, should, therefore, be larger than in the preceding pairs, and likewise must the mandrel be of successively larger diameter between the successively wider roll openings. The action and effect of a mandrel of successively larger diameter between the successively wider roll openings are of great importance in the expanding of the billet or tube. It will be seen that if the mandrel were of the same uniform diameter between all the roll pairs the tube which was reduced in. thickness of wall and enlarged in diameter by the first acting roll pair would thenby the succeeding pairs have to be considerably compressed or crushed into a very pronounced oval shape before any actual reduction of the wall between the roll faces and the mandrel and any further elongation and expansion would take place in said succeeding pairs. The result would be great play between the mandrel and the inside of the billet or tube in the direction opposite to that in which the billet is compressed between the working roll surfaces and the mandrel,- a-nd, consequently, great difliculty in properly holding the tube and mandrel in alinement in the pass line by suitable.

guides. This difliculty or inconvenience will become very serious when a number of roll pairs are used to accomplish a great total expansion, andwhen the expansion is progressively increased between a number of simultaneously acting pairs of rolling bodies. The less play there is at any point between the mandrel and the inside of the billet or tube, the easier it will be to hold both in a given alinement with the axis of the pass andto maintain constant eccentricity between rolls and billet and consequent constant feed effect by alt roll pairs.

On account of theprogressively larger cylindrical portions of the mandrel, it will be evident that the mandrel cannot be left with the billet, and that it must either be held stationary endwise or must be left to advance only such a restricted distance that T the portion of the mandrel which is of appropriate diameter to act between any one of the roll pairs shall not advance beyond the pass between the working faces of said rollpair during the cross rolling of a billet or tube its full lcngtlr by such pair. Vhet-her'the mandrel bar be heldendwise stationary or be allowed to advance in restricted measure, it is preferable that it be allowed to r'evolve freely with the billet or tube.

The controllingof the motion of the man- 6 rel bar as described is easily and simply accom plishcdwith the arrangement shown in Figs. 1 and 2 as follows: The front part of cylinder N is by means of pipe R and valve S connected with a reservoir containing iiuid under pressure; if the valve 8' is adjusted so that there is no communication between the cylinder N and said reservoir, then the fluid contained in said cylinder between piston M and valve S( cannot escape and the piston M cannot advance, and the mandrel bar J, which turns lefthandedly adjusted as tolet the fluid escape slowly from the cylinder ahead of the piston M, the mandrel bar, which by the action of the va rious roll pairs has the tendency to rotate andtravel endwise forward with the billet, pulls forward with considerable force the piston M, and the pressure of the fluid in the reservoir being conditioned so that it is less than the compression resulting from the forward pull of the mandrel bar, the fluid will then slowly escape from ahead of the piston M, and the piston M and the mandrel bar will be allowed to slowly travel endwise forward. As soon as the billet or tube has passed through all of the roll pairs and has been rolled completely, as shown in Fig. 2, the mandrel bar is no more subject to any forward endwise pull. and the pressure fluid will return from the reservoir intothe cylinder N and move baclrthe piston lVI and the mandrel bar J, the latter beingthus automatically, without any further aid or effort, and immediately upon the completion of the rolling of the tube. com' pletely withdrawn from the tube. so that the tube can at once he removed from the pass line. The mandrel bar is then unscrewed from spindleG. a fresh billet is placed on the mandrel bar. the latter is again screwed to the spindle G,-and the roll ing of the fresh billet can then be started.

It is preferable to let the mandrel bar ;advance endwise in a restricted measure as described. particularly in cases where small tubes of long lengths have to be rolled. It will be evident that in such cases the mandrel bar is liable to heat and then to yield under the rolling pressure if said pressure is ex- :erted at the same place on the mandrel bar during the entire rolling operation of the full length of the tube. Such heating ofthe mandrel bar'and its yielding under the rolling pressure is not as liable to occur if the mandrel bar has a slow endwise forward imotion. so that fresh portions 32 it. are successively and continuously submitted to the close contact with the hot metal. of the billet f under rolling pressure.

Referring to Figs. 1 and 3. it will be understood that the endwise advance of the mandrel bar must be restricted in such a manner that the respective pairs of rolling bodies have coacting between their working faces the same diameter of mandrel during their rolling of the full length of the tube. To fulfil this condition, it will be seen that ill) '- from the pass line.

the endwise travel of the mandrel bar is necessarily less than the distance between the passes of successive pairs of acting working faces. It will now be seen that under the process in most preferred form as described, the billet is cross rolled at first by one roll pair, then by two pairs simultaneously, then by three pairs simultaneously; also that the cross rolling is progressive and simultaneous upon different diameters of the billet while supported internally by a mandrel bar of appropriate different diameters at the respective roll pairs, and that the metal is spread in the first roll pair and mandrel bar both longitudinally and transversely or circumferentially, and expanded and elongated and passed onto the succeeding larger diameter of the bar, there to be further expanded and elongated, and, lastly, it is smoothed out on the largest portion of the mandrel bar.

lilanifestly, in the process described with Figs. 1 and 2, the mandrel bar is subjected to tension. In Figs. 3 and 4 is shown a method of controlling the mandrel bar by which the latter, instead of being held at its rear or small end, as in Figs. 1 and 2, is supported at its front end and is subjected to endwise compression instead of tension.

Referring to these Figs. 8 and 4, the mandrel bar J and the tube K are shown in their respective positions in relation to the roll pairs at the moment the rolling operation of the tube,has been completed. The slide head H is connected topiston rod U, which has its piston movable in a suitable double-acting cylinder V. The frame or table 0, thepiston rod U and the cylinder V are of sufficient length to, and serve to, quickly and entirely withdraw the mandrel bar forward from the tube and again return it thereafter backward in its initial working position after the tube has been removed The operation of the mandrel bar by cylinder V in this case I prefer to accomplish by the use of compressed air or steam, thus obtaining quicker action than with a liquid under pressure. In order to obtain a restricted travel of the mandrel bar during the rolling operation of the tube, similarly to the manner described -:-;upply pipe and valve R and S, performs the same functions as those previously described for the similar parts of Figs. 1 and 'hen it is desired to withdraw the mandrel bar from the completed rolled tube,

' the latch Y is, by the aid of hand levers Z,

\vitluh-awn from the notch W in head H, and the latter with the mandrel bar can then with the aid of cylinder V be quickly withdrawn forward (to the right) until the mandrel bar is disengaged from the tube, the tube is then removed from the pass line and the mandrel bar is again returned between the rolls until the spring latch snaps into its seat or notch V inthe head H. A fresh billet is then introduced over the small end of the mandrel bar and between the rolls and the travel forward of the mandrel bar is then again under control at will by regulating the valve S, as described with reference to Figs. 1 and 2.

It will be seen that the method of supporting the mandrel bar at its'front end, as shown in Figs. 3 and 4, necessitates a much longer mandrel bar thanif it is held at its rear or mall end as shown in Figs. 1 and 2. And, inasmuch as the short mandrel bar is subjected to tension and the long bar to compression endwise, it follows that the arrangement of a mandrel. bar under tension and held at its small end, as shown in Figs. 1 and 2, is more suitable in the rolling of long tubes; while that of a mandrel bar supported at its other end under compression, as shown in Figs. 3 and 4, becomes more practical in the rolling of short tubes.

Referrin to the arrangement of holding the mandrel bar and of controlling its endwise travel, as shown in Figs. 3 and 4, it will be. understood that the action of two independent cylinders V and N is of great advantage. as it enables me, as soon as the tube is rolled, to quickly and simply manipulate the mandrel bar to remove the rolled tube and to reintroduce the mandrel bar in its working position between the roll pairs and into a fresh hollow billet at the first roll pair, and the short stroke cylinder N provides for allowing the mandrel bar the necessary restricted endwise travel. Billets or tubes of widely different diameters can, of course, be rolled by this process in the same rolls by simply adjusting the rolls along their axes so as to change the width of the pass formed between their working faces.

Instead of curved convex working faces on the rolls, substantially angular faces comprising straight-line components forming a V-shaped section, as illustrated in Fig. 7, and giving an angular form of convexity, may be used, and I use the term convex to include such angular forms. In either form the pass between the two rolls of one.

pair is slowly convergent and then slowly divergent, in order to permit only a restricted endwise flow of the metal, and to thereby increase the expansion of the billet. The sucessive roll pairs are placed as close to each other as convenient, in order that they may act simultaneously on the billet for a longer time and greater length than if they were farther apart. A greater or less number of roll pairs may be employed, according to the total amount of reduction in wall thickness of the billet which is desired, but I prefer to use at least two or more pairs be-- sides the last, or smoothing rolls, making at least three pairs, as shown.

In the process described, it will be seen i that in the manufacture of tubes of a given diameter by expanding them, much smaller hollow billets can be employed than when 1 the process of manufacture consists in only I the billet by an excess endwise feed eifect' of the rolls in order to eliminate or reduce any expansion that the billetv would nor mally assume, even if the rolls are provided with convex working faces short longitudinally of the pass.

The process is in no wise limited to the details shown in Figs. 1 to 4:, inclusive. For example, in Fig. 5 there is illustrated a pair of disk-shaped rolls for cross rolling which revolve in opposite directions and which are placed opposite each other, as shown and'as will be well understood, instead of being overlapped, as in Figs. 1, 2 and 3. In Fig. 6, barrel-shaped rolls are illustrated, arranged. as Wlll be understood, to give the same effects and serve the same purpose as one pair of' the overlapped diskshaped rolls of Figs. 1, 2 and 3.

lVhere the expansion of the tube upon the mandrel bar is to be but slight and the pierced billets are loose enough to be passed over the largest portion of the mandrel, the process may be carried out by the means shown in Figs. 8 and 9, whereby the mandrel bar is operated from the rear and after a tube leaves the last rolls the mandrel is Withdrawn backward from the tube and out through the entire length of the pass, and then inserted into the rear end of the succeeding billet and returned forward to its proper initial position between the rolls, causing the front of the billet to enter between the first rolls. In Fig. 9, the parts are shown in position when the rolling of the billet has just terminated. V is the long steam cylinder for drawing the cross head H and the mandrel bar J backward and then thrusting it forward again into its initial place through the next billet, and N is the shortholdingback cylinder with its plunger L, of length suiiicientfor suitably retarding the mandrel during the cross rolling, as already explaine In this instance a the plunger L merely abuts against the cross head H to resist the movement, and no provision for latching and unlatching it, as in Fi 4, is required.

Lemp oy the terms billet and tube interchangeably to include the tubular billet I or tube at any part of its manufacture.

I claim the following:

1. The process of cross rolling a tube which comprises progressively and simultaneously cross rolling the tube at a plurality of difierent portions of different diameter by a plurality of pairs of rolling bodies having progressively increasing ratios between the feeding and the rotatory rolling components and a mandrel bar having different diameters, such cross rolling spreading the metal both longitudinally and transversely at one or more of the pairs by roll ing faces that are convex longitudinally, the metal advancing over the bar and in a succeeding pair being cross rolled on a larger diameter of the mandrel bar.

2. The process of cross rolling a tube which comprises progressively and simultaneously cross rolling the tube at a plu rality of different port-ions of difierent diameter by a plurality of pairs of rolling bodies having progressively increasing ratios between the feeding and the rotatory rolling components and a mandrel bar having different diameters, such cross rolling spreading the metal both longitudinally and transversely at one or more of the pairs by rolling faces that are convex longitudinally. the metal advancing over the bar and in a succeeding pair being cross rolled on a larger diameter of the mandrel bar, and toward the exit of the pass'smoothing the tube between substantially straight, parallel faces.

3. The process of cross rolling a tube which comprises progressively and simultaneously cross rolling the tube at a plurality of different portions of different diameter by a plurality of pairs of rolling bodies and a mandrel bar having different diameters, such cross rolling spreading the metal tube at a plurality of different portions ot' its length upon a mandrel bar of progressively larger diameters at such portions and with progressively increasing ratios of feeding to rotating rolling components.

5. The process of cross rolling a tube which comprises progressively and simultaneously cross rolling and expanding the tube at a plurality of different portions of its length upon a mandrel bar of progressively larger diameters at such'portions, and

holding back the mandrel bar relatively to the tube While allowing it to turn freely.

6. Apparatus for progressively and simultaneously cross rolling and expanding tubes at a plurality of points comprising a plurality of pairs of cross rolling bodies hav- .ing convex rolling faces and having progressively Wider passes between them, a mandrel bar, and means for holding back the mandrel bar relatively to the tube.

7. Apparatus for progressively and simultaneously cross rolling and expanding tubes taneously cross rolling and expanding tubes at a plurality of points comprising a plurality of pairs of cross rolling bodies having convex rolling faces and having progressively Wider passes between them, a mandrel bar therefor, and power-actuated means smoothing rolls having faces substantially -f fiat longitudinally of the pass.

10.'Apparatus for progressively and simultaneously cross rolling tubes at a plurality of points comprising a plurality of pairs of cross rolling bodies and a coiiperating mandrel bar, means for actuating the mandrel bar lengthwise of the pass out of and into the billets, and additional means for holding back the mandrel bar during rolling.

In testimony whereof I have signed this specification in the presence of two subscribing Witnesses this 24: day of June, 1912.

RALPH CHARLES STIEFEL. 

